Bombus

.

B. humilis worker visiting Cirsium.

Thoracobombus ecology and behaviour   HABITAT: Open grassland, mountain meadow, semi-desert, and tropical montane and lowland forest, less often in temperate forests. Thoracobombus includes the only species of bumblebees occurring in lowland tropical wet forest.   FOOD-PLANTS: Medium to long tongue-length bumblebees visiting medium to deep flowers.   NESTING BEHAVIOUR: Nests on the surface or sometimes underground. Pocket-makers, although sometimes only early in colony development, or sometimes non-pocket makers. Nests may be underground but are often on the surface in balls of grass or leaves collected by the bees (hence the name 'carder' bees used for some of the species; Sladen, 1912). Colonies of some Neotropical species may be large and particularly aggressive. Some of the Neotropical tropical lowland forest species have colonies that persist for more than one year, with large nests on the surface of the ground. One species, B. inexspectatus, is believed to be an obligate parasite in colonies of other species (Müller, 2006).   MATE-SEARCHING BEHAVIOUR: Males patrol circuits of scent marks. Males of some species congregate at the entrances of nests to pursue emerging queens.

Subgenus THORACOBOMBUS Dalla Torre
Bombus (Rhodobombus) Dalla Torre, 1880:40, type-species Bremus pomorum Panzer (= Bombus pomorum (Panzer)) by subsequent designation of Sandhouse, 1943:596
Bombus (Thoracobombus) Dalla Torre, 1880:40, type-species Apis sylvarum Linnaeus (= Bombus sylvarum (Linnaeus)) by subsequent designation of Sandhouse, 1943:604
Bombus (Chromobombus) Dalla Torre, 1880:40, type-species Apis muscorum Linnaeus (= Bombus muscorum (Linnaeus)) by subsequent designation of Sandhouse, 1943:538
Bombus (Agrobombus) Vogt, 1911:52, type-species Apis agrorum Fabricius (= Bombus pascuorum (Scopoli)) by subsequent designation of Sandhouse, 1943:523
[Agrabombus Skorikov, 1914a:119, incorrect subsequent spelling]
Bombus (Pomobombus) Krüger, 1917:65, type-species Bremus pomorum Panzer (= Bombus pomorum (Panzer)) by subsequent designation of Sandhouse, 1943:589
Mucidobombus Krüger, 1920:350, type-species Bombus mucidus Gerstaecker by monotypy
Bombus (Laesobombus) Krüger, 1920:350, type-species Bombus laesus Morawitz by monotypy
Bombus (Ruderariobombus) Krüger, 1920:350, type-species Apis ruderaria Müller (= Bombus ruderarius (Müller)) by subsequent designation of Yarrow, 1971:27
Agrobombus (Laesobombus) Skorikov, 1922:20, type-species Bombus laesus Morawitz by monotypy
Agrobombus (Adventoribombus) Skorikov, 1922:24, type-species Apis sylvarum Linnaeus (= Bombus sylvarum (Linnaeus)) by subsequent designation of Yarrow, 1971:28.
Mucidobombus (Exilobombus) Skorikov, [1923]:150, type-species Mucidobombus exil Skorikov (cited as exiln.) (= Bombus exil (Skorikov)) by monotypy
Agrobombus (Tricornibombus) Skorikov, [1923]:151, type-species Bombus tricornis Radoszkowski by monotypy
Fervidobombus Skorikov, [1923]:153, type-species Apis fervida Fabricius (= Bombus fervidus (Fabricius)) by subsequent designation of Frison, 1927:69
[Agrobombus (Adventoriobombus) Skorikov, 1931:218, incorrect subsequent spelling]
Pomibombus Skorikov, 1938a:145, unjustified emendation
Agribombus Skorikov, 1938a:145, unjustified emendation
Agribombus (Laesibombus) Skorikov, 1938a:145, unjustified emendation
Agribombus (Eversmannibombus) Skorikov, 1938a:145, type-species Mucidobombus eversmanniellus (= Bombus persicus Radoszkowski) by monotypy
Megabombus (Exilnobombus) Milliron, 1973a:81, unjustified emendation
[Bombus (Thoraocbombus) Esmaili & Rastegar, 1974:52, incorrect subsequent spelling]
Bombus (Digressobombus) Laverty et al., 1984:1051, type-species Megabombus digressus Milliron (= Bombus digressus (Milliron)) by original designation
[Bombus (Thoracibombus) Schwarz et al., 1996:197, incorrect subsequent spelling]

NOMENCLATURE: There has been uncertainty regarding the relative publication dates of two of Skorikov's papers: on Palaearctic bumblebees (part 1); and on the Bumblebees of the Petrograd province. The cover of the Palaearctic paper is marked November, 1922, and the preface is signed 15 November 1922, whereas the Petrograd paper is marked simply 1922. According to Y. Pesenko (in litt.; see also Pesenko & Astafurova, 2003), it is required by Russian law that all books and periodicals must be sent to the 'Book Chronicle' (Knizhnaya letopis) immediately after printing for listing. He found that publication of the Petrograd paper was listed for November-December 1922 (giving a publication date, by convention, of 31 December 1922), whereas publication of the Palaearctic paper was listed for 1-15 October 1923 (publication date, by convention, of 15 October 1923). Yarrow's (1971) designation of Apis sylvarum Linnaeus (= B. sylvarum (Linnaeus)) as type-species for Adventoribombus Skorikov is then valid, because Agrabombus adventor Skorikov (= B. filchnerae Vogt) (designated as type-species by Sandhouse, 1943) was not originally included in the Petrograd paper and therefore cannot be the type-species. This makes Adventoribombus an objective junior synonym of Thoracobombus.

TAXONOMIC STATUS: For a discussion of why several former subgenera have been synonymised within this subgenus see Williams et al. (2008 [pdf]).

Part of the bumblebee phylogenetic tree including available Thoracobombus species from an analysis of DNA sequence data for five genes (Cameron et al. 2007 [pdf]). Values above branches are Bayesian posterior probabilities, values below branches are parsimony bootstrap values. Alternative resolution from parsimony analysis is shown with dotted lines.

morio-group of species

Bombus (Th.) dahlbomii Guérin-Méneville
Dahlbomii Guérin-Méneville, [1835, see Cowan, 1971:29]:pl.75
nigripes Haliday in Curtis et al., 1836:321
4 names

NOMENCLATURE: Cowan (1971), considering Guérin-Méneville's insect volume, states that 'it is quite certain that valid publication [of the Insectes text] under the International Code of Nomenclature did not take place until August or September 1844.' However, he lists plate 75, on which B. dahlbomii appears as figure 3 together with a legend containing the name, as having been published in livraison 39 in June 1835. This meets the criteria for valid publication (ICZN, 1999: Article 8). Therefore B. dahlbomii is the oldest available name for this species.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: S Neotropical Region, E Neotropical border.

Bombus (Th.) morio (Swederus)
morio (Swederus, 1787:283 [Apis]) examined
velutinus Illiger, 1806:175
violaceus Lepeletier, [1835]:473
carbonarius Handlirsch, 1888:241, not of Menge, 1856:27 [fossil]
Kohli Cockerell, 1906:75, replacement name for carbonarius Handlirsch, 1888:241
7 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: W Neotropical, E Neotropical Regions.

Bombus (Th.) excellens Smith
excellens Smith, 1879:133, examined
2 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: W Neotropical Region.

pomorum-group of species

Bombus (Th.) pomorum (Panzer)
pomorum (Panzer, 1805(86):18 [Bremus])
Lefebvrei Lepeletier, [1835]:461
42 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region. B. pomorum has been recorded from Britain (last recorded in 1864), but possibly only as a rare immigrant (Alford, 1975) (see also declines in British bumble bees).

NOTES on this species in Britain.

Bombus (Th.) mesomelas Gerstaecker
Agrorum (Schrank, 1781:397 [Apis])
arvenfis [arvensis] (Gmelin in Linnaeus, 1790:2786 [Apis]) unjustified replacement name for agrorum Schrank, 1781:397
mesomelas Gerstaecker, 1869:321
6 names

NOMENCLATURE: The orthography of Linnaeus (1790) employs a long 's' (similar to 'f' or 'f'), a common practice of the period. This convention has since changed and recent authors have consistently used 's'.

Warncke (1986) listed B. agrorum (Schrank) as questionably conspecific with B. distinguendus, presumably following Benson et al. (1937). Although I know of no extant type specimens, Schrank's (1781) description of his B. agrorum of 'Habitat ruri' from Austria appears to me to be almost certainly of the same species as B. mesomelas, because the head is described as black and the pale hairs of the thorax and of gastral tergum I are described as grey, with the remainder of the gaster rusty or tawny-yellow (the head and the pale pubescence of the thorax and gaster are more uniformly dull yellowish for B. distinguendus). See the comments on B. distinguendus.

Although B. agrorum (Schrank) is the oldest available name for the present interpretation of this species, I know of no publications since 1950 using this name. In contrast, the name B. mesomelas has remained in common use (e.g. Tkalcu, 1969, 1975; Delmas, 1976; Reinig, 1974, 1981; Özbek, 1983; Rasmont, 1983; Ornosa, 1986a, b; Rasmont et al. 1987, 1995). This follows the recommendation of Benson et al. (1937) that the name B. agrorum (Fabricius), which had been in widespread use for a species of the subgenus Thoracobombus, should not be replaced. Benson et al. (1937:94) had expressed their intention to make an application to ICZN to use its Plenary Power to suppress the unused senior synonym, B. agrorum (Schrank), but it was never pursued. O. W. Richards must subsequently have changed his opinion, because he went on to use the name B. pascuorum for the species of the subgenus Thoracobombus (Richards, 1968). It is suggested that, in the interests of stability (ICZN, 1999: Article 23), prevailing usage be maintained (in prep.).

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region.

Bombus (Th.) armeniacus Radoszkowski
armeniacus Radoszkowski, 1877b:202
8 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region, Oriental border.

mucidus-group of species

Bombus (Th.) laesus Morawitz
laesus Morawitz in Fedtschenko, 1875:3, examined
Mocsáryi [mocsaryi] Kriechbaumer, 1877:253
Sidemii Radoszkowski, 1888:321
[maculidorsis (Skorikov, 1922:23 [Agrobombus]) infrasubspecific]
?tianschanicus Panfilov, 1956:1327
?maculidorsis Panfilov, 1956:1328, examined
ferrugifer Reinig, 1971:158
11 names

TAXONOMIC STATUS: Panfilov (1956) regarded B. laesus, B. mocsaryi, B. maculidorsis and B. tianschanicus as separate species, differing particularly in: (1) the colour of the pubescence on the thoracic dorsum; (2) the number of large punctures on the clypeus; (3) the strength of the median keel on gastral sternum VI; and (4) the length of the hair of the dorsum. However, from the material I have examined (collections in London, Moscow, Beijing), these character states do not appear to be either discreet or strongly associated. Until more evidence to the contrary is available from critical studies of patterns of variation, I shall treat them as parts of a single variable species.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic, Oriental Regions.

Bombus (Th.) mucidus Gerstaecker
mucidus Gerstaecker, 1869:324
atratus Friese, 1911:572, examined
9 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region.

Bombus (Th.) persicus Radoszkowski
calidus Eversmann, 1852:133, examined, not of Erichson in Middendorff, 1851:65 (= B. hypnorum (Linnaeus))
persicus Radoszkowski, 1881:v, examined
Persicus Radoszkowski, 1883:214, redescribed
eversmanni Friese, 1911:572, not of Skorikov, 1910c:581 (= B. modestus Eversmann), replacement name for calidus Eversmann, 1852:133
eversmanniellus (Skorikov, [1923]:149 [Mucidobombus]) replacement name for eversmanni Friese, 1911:572
10 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region.

muscorum-group of species

Bombus (Th.) filchnerae Vogt
Filchnerae Vogt, 1908:100, examined
adventor (Skorikov, 1914a:119 [Agrabombus])
lii Tkalcu, 1961b:355
5 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic, Oriental Regions.

Bombus (Th.) muscorum (Linnaeus)
Mufcorum [muscorum] (Linnaeus, 1758:579 [Apis]) examined
pallidus Evans, 1901:47, not of Cresson, 1863:92 (= B. pensylvanicus (DeGeer))
[fulvofasciatus Friese, 1905:520, infrasubspecific]
laevis Vogt, 1909:63
?nigripes Pérez, 1909:158, not of Haliday in Curtis et al., 1837:321 (= B. dahlbomii Guérin-Méneville)
pereziellus (Skorikov, [1923]:150 [Agrobombus]) replacement name for nigripes Pérez, 1909:158
?bannitus (Skorikov in Popov, 1930:98 [Agrobombus])
?liepetterseni Løken, 1973:152
celticus Yarrow, 1978:15, replacement name for pallidus Evans, 1901:47
agricolae Baker, 1996a:14,19
17 names

TAXONOMIC STATUS: The taxon bannitus in the broad sense (= B. smithianus of authors, a misidentification (= B. pascuorum)), including agricolae for the British forms from the Outer Scottish Isles and Shetland, has been regarded as a separate species by some authors (e.g. Richards, 1935; Tkalcu, 1987; Rasmont & Adamski, 1995) on the basis of its semi-melanic colour pattern and more coarsely sculptured surface of gastral terga IV-V. However, Løken (1973: fig. 81) found no difference between these taxa in a morphometric study (other authors reporting no clear morphological differences include Richards, 1935; Alford, 1975; Pekkarinen, 1979; Rasmont, 1982; Baker, 1996a) and I have collected many specimens with a range of intermediate colour patterns on the Isle of Skye in western Scotland. Until more evidence to the contrary is available from critical studies of patterns of variation, I shall treat them as parts of a single variable species.

The taxon pereziellus has also been regarded as a separate species by Rasmont & Adamski (1995), because of its dark colour pattern (even darker than the taxon bannitus, pereziellus has the thoracic dorsum black rather than red-brown, and has more black hairs on gastral tergum II, whereas these black hairs tend to be more frequent on tergum I for bannitus) and because it is endemic to the island of Corsica. Morphologically the taxon pereziellus was considered by Rasmont (1982) to show no perceptible differences from B. muscorum or bannitus. Furthermore, a male with a colour pattern apparently intermediate between B. muscorum and pereziellus is mentioned by Delmas (1976:271). Depending on the species concept embraced, some differences might be expected for a peripheral population such as this even if it were conspecific. A more recent study of the taxon pereziellus in comparison with B. muscorum in neighbouring Europe by Lecocq et al. (2014) concluded that pereziellus is an endemic Corsican subspecies.

NOMENCLATURE: The orthography of Linnaeus (1758) employs a long 's' (similar to 'f' or 'f'), a common practice of the period. This convention has since changed and recent authors have consistently used 's'.

Richards (1935, 1968), Yarrow (1968) and Løken (1973) recognised that none of the admissable syntypes in the Linnean collection agreed with the traditional interpretation of B. muscorum, which is very rare in the parts of Sweden where Linnaeus collected (Richards, 1935; Løken, 1973; Day, 1979), but took no action. When Day (1979) came to fix the application of the name, he had no reason to believe that Linnaeus had not described his A. muscorum from the syntype specimen that was subsequently described as lectotype (= B. humilis Illiger).

To reaffirm the traditional usage of B. muscorum, a case was made to ICZN by Løken et al. (1994). This sought an Opinion from ICZN (ICZN, 1996) that set aside by use of its Plenary Power (ICZN, 1985: Articles 78b, 79) the lectotype designation for A. muscorum by Day from application of the Code (ICZN, 1985) and then designated a neotype (ICZN, 1996: 64) to conserve the traditional usage of the name for even the narrowest concept of the taxon (ICZN, 1985: Article 75) (in prep.).

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region.

NOTES on this species in Britain.

Bombus (Th.) anachoreta (Skorikov)
anachoreta (Skorikov, 1914a:121 [Agrobombus])
3 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic, Oriental Regions.

Bombus (Th.) opulentus Smith
opulentus Smith, 1861:153, examined
2 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic, Oriental Regions.

Bombus (Th.) zonatus Smith
zonatus Smith, 1854:389
15 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region.

Bombus (Th.) velox (Skorikov)
velox (Skorikov, 1914a:120 [Agrobombus])
1 name

DISTRIBUTION: Palaearctic.

Bombus (Th.) ruderarius (Müller)
ruderaria (Müller, 1776:165 [Apis])
Derhamella (Kirby, 1802:363 [Apis]) examined
montanus Lepeletier, [1835]:463
?simulatilis Radoszkowski, 1888:317, examined
64 names

TAXONOMIC STATUS: Recent studies of the secretions of the male cephalic glands by Terzo et al. (2005) provide strong support for the interpretation that B. ruderarius and B. montanus are conspecific and a species separate from B. sylvarum.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region.

NOTES on this species in Britain.

Bombus (Th.) veteranus (Fabricius)
veterana (Fabricius, 1793:324 [Apis])
arenicola Thomson, 1872:31
8 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region.

Bombus (Th.) mlokosievitzii Radoszkowski
Mlokosievitzii Radoszkowski, 1877a:viii
Mlokassewiczi Radoszkowski, 1877b:212, redescribed
pérezi [perezi] Vogt, 1911:55, not of Schulthess-Rechberg, 1886:275 (= B. perezi (Schulthess-Rechberg))
vogtiellus (Tkalcu, 1977:224 [Megabombus]) replacement name for perezi Vogt, 1911:55
[mlokossowiczi (Reinig, 1981:161 [Megabombus]) incorrect subsequent spelling]
15 names

NOMENCLATURE: There are particularly many incorrect subsequent spellings of B. mlokosievitzii.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region.

Bombus (Th.) sylvarum (Linnaeus)
fylvarum [sylvarum] (Linnaeus, 1761:425 [Apis]) examined
Daghestanicus Radoszkowski, 1877a:vii
Dagestanicus Radoszkowski, 1877b:211, redescribed
23 names

NOMENCLATURE: The orthography of Linnaeus (1761) employs a long 's' (similar to 'f' or 'f'), a common practice of the period. This convention has since changed and recent authors have consistently used 's'.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region.

NOTES on this species in Britain.

Bombus (Th.) inexspectatus (Tkalcu)
lutescens Krüger, 1939:105, not of Pérez, 1890:154 (= B. flavidus Eversmann)
inexspectatus (Tkalcu, 1963:187 [Agrobombus])
[inexpectatus (Reinig, 1981:161 [Megabombus]) incorrect subsequent spelling]
3 names

COMMENT: On the grounds of its peculiar morphology, this species was suggested by Yarrow (1970) to be an obligate 'workerless' social parasite in colonies of other Bombus species, most probably of B. ruderarius. B. inexspectatus has since been found in a nest of B. ruderarius (Müller, 2006), although detailed observations of behaviour are still needed. Yarrow (1970) interpreted two worker-sized individuals of B. inexspectatus from Switzerland and Italy as likely to be over-wintered 'runt females'. He also described another two worker-sized females he collected in May or early June from France and Spain (in the NHM collection), although he argued that these too are dwarf over-wintered females (in the sense of gynes). See the comments on the subgenus Psithyrus and on B. hyperboreus.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region.

Bombus (Th.) deuteronymus Schulz
senilis Smith, 1879:131, examined, not of Fabricius, 1775:382 (= B. pascuorum (Scopoli))
deuteronymus Schulz, 1906:267, replacement name for senilis Smith, 1879:131
[superequester (Skorikov, 1914c:405 [Agrobombus]) infrasubspecific]
superequester (Skorikov, 1926:116 [Agrobombus])
bureschi Pittioni, 1939b:1, examined
13 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic, Japanese, Oriental Regions.

Bombus (Th.) humilis Illiger
?fulvefcens [fulvescens] (Schrank, 1802:367 [Apis])
humilis Illiger, 1806:171, examined
tristis Seidl, 1837:69
variabilis Schmiedeknecht, 1878:424, not of Cresson, 1872:284 (= B. variabilis (Cresson))
subbaicalensis Vogt, 1911:42,54, examined
100 names

NOMENCLATURE: The orthography of Schrank (1802) employs a long 's' (similar to 'f' or 'f'), a common practice of the period. This convention has since changed and recent authors have consistently used 's'.

When Day (1979) came to fix the application of A. muscorum Linnaeus (see the comments on B. muscorum), he had no reason to believe that Linnaeus had not described this taxon from the syntype specimen that was subsequently described as lectotype (= B. humilis Illiger). This action brought B. humilis Illiger into subjective junior synonymy with B. muscorum (Linnaeus).

To reaffirm the traditional usage of B. muscorum and B. humilis, a case was made to ICZN by Løken et al. (1994). This sought an Opinion from ICZN (ICZN, 1996) that set aside by use of its Plenary Power (ICZN, 1985: Articles 78b, 79) the lectotype designation for A. muscorum by Day from application of the Code (ICZN, 1985) and then designated a neotype (ICZN, 1996: 64) to conserve the traditional usage of B. muscorum and B. humilis (ICZN, 1985: Article 75).

However, Warncke (1986) recognised B. fulvescens (Schrank) as questionably conspecific with B. humilis. I have seen no type specimens, but the description is consistent with this interpretation. B. fulvescens is therefore likely to be the oldest available name for this species.

Although B. fulvescens may be the oldest available name for the present interpretation of this species, the name B. humilis has been in common use for the species since 1950 (e.g. case and references in Løken et al., 1994). In contrast, I know of no publications using the name B. fulvescens (Schrank) since 1950. Warncke (1986:98) followed the listing of this name with 'Art. 23b', which is a reference to purpose of the Principle of Priority (ICZN, 1985). I agree that, in the interests of stability (ICZN, 1999: Article 23), prevailing usage be maintained (see the comments on B. muscorum) (in prep.).

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic, Oriental Regions.

NOTES on this species in Britain.

Bombus (Th.) pascuorum (Scopoli)
Pafcuorum [pascuorum] (Scopoli, 1763:306 [Apis])
fenilis [senilis] (Fabricius, 1775:382 [Apis])
agrorum (Fabricius, 1787:301 [Apis]) not of Schrank, 1781:397 (= B. mesomelas Gerstaecker)
thoracicus Spinola, 1806:30
arcticus Dahlbom, 1832:50, not of Quenzel in Acerbi, 1802:253 (= B. hyperboreus Schönherr)
cognatus Stephens, 1846:17, examined
smithianus White, 1851:158
112 names

TAXONOMIC STATUS: Warncke (1986) listed B. cognatus as a synonym of B. muscorum, possibly following Stephens (1846), who wrote of B. cognatus: 'Closely allied to Bo. Muscorum, of which the examples I possess may be immature specimens'. Pagliano (1995) listed B. cognatus as a species separate from both B. muscorum and B. pascuorum, but without any explanation.

Saunders (1896:366-367) wrote 'I have re-examined the type of cognatus, Steph., ... F. Smith placed it in the British Museum collection ...'. Saunders considered this specimen to be conspecific with B. agrorum (Fabricius), continuing: 'It is certainly not the species known on the Continent as cognatus'.

A female in the NHM collection bears the following labels: (1) a red-edged printed 'Type'; (2) 'cognatus.' in handwriting identical to that of F. Smith; (3) '= agrorum / I.H.H.Y.' in handwriting identical to that of I. Yarrow; (4) 'B.M. Type / HYM. / 17B.1163'. I have examined this specimen and am unaware of any reason (other than minor differences in colour pattern) why it should not be considered the type of B. cognatus and conspecific with B. pascuorum.

NOMENCLATURE: The orthography of Scopoli (1763) and Fabricius (1775) employs a long 's' (similar to 'f' or 'f'), a common practice of the period. This convention has since changed and recent authors have consistently used 's'.

Løken (1973) listed B. cognatus Stephens, 1846, as a nomen nudum, citing Sherborn (1925). However, the reference by Sherborn is to Stephens (1829), therefore this does not affect the use of the name B. cognatus Stephens, 1846.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region.

NOTES on this species in Britain.

Bombus (Th.) honshuensis (Tkalcu)
honshuensis (Tkalcu, 1968a:47 [Megabombus])
2 names

TAXONOMIC STATUS: B. honshuensis and B. schrencki have allopatric distributions in northern Japan (Sakagami & Ishikawa, 1969; Ito & Munakata, 1979: fig. 6; Ito, 1993), with B. honshuensis being possibly a peripheral population of B. schrencki. The two taxa are closely similar, although despite variation in morphology, apparently consistent differences have been described (Tkalcu, 1968a; Sakagami & Ishikawa, 1972).

DISTRIBUTION: Japanese Region.

Bombus (Th.) schrencki Morawitz
Schrencki Morawitz, 1881:123
Schrencki Morawitz, 1881:250, redescribed
konakovi Panfilov, 1956:1330
9 names

TAXONOMIC STATUS: See comments on B. honshuensis.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic, Japanese, Oriental Regions. This species is reported as spreading westwards in Europe (Pawlikowski, 1994).

Bombus (Th.) hedini Bischoff
unicolor Friese, 1905:514 examined not of Kriechbaumer, 1870:159 (= B. maxillosus Klug)
hedini Bischoff, 1936:15
2 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic, Oriental Regions.

Bombus (Th.) pseudobaicalensis Vogt
Pseudobaicalensis Vogt, 1911:43,53
gilvus (Skorikov, 1926:117 [Agrobombus])
3 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic, Japanese Regions.

Bombus (Th.) remotus (Tkalcu)
remotus (Tkalcu, 1968a:45 [Megabombus]) examined
1 name

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Oriental Region.

Bombus (Th.) impetuosus Smith
impetuosus Smith, 1871:249, examined
Potanini Morawitz, 1890:350
yuennanensis Bischoff, 1936:14, examined
combai Tkalcu, 1961b:357
9 names

TAXONOMIC STATUS: The white-banded B. potanini is morphologically closely similar to the yellow-banded B. impetuosus. Some individuals from Sichuan are intermediate in colour pattern in that they have the pale bands of the thorax and gastral tergum I white, and the pale band of tergum II yellow. There is considerable variation in the male gonostylus, but this variation appears to overlap between the the colour forms and I shall treat them as parts of a single variable species. S.-f. Wang and J. Yao (in litt.) also believe that the two taxa are conspecific. Evidence from comparisons of DNA sequences from five genes is consistent with the two taxa being conspecific (Cameron et al., 2007 [pdf]). Further evidence is awaited.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Oriental Region.

imitator-group of species

Bombus (Th.) imitator Pittioni
imitator Pittioni, 1949:251, examined
flavescens Pittioni, 1949:254, not of Smith, 1852a:45 (= B. flavescens Smith)
3 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Oriental Region.

atripes-group of species

Bombus (Th.) exil (Skorikov)
exiln. nov. (Skorikov, [1923]:150 [Mucidobombus]) [not a replacement name]
[exul (Skorikov, 1931:216 [Mucidobombus]) incorrect subsequent spelling]
exil (Milliron, 1961:56 [Megabombus]) justified emendation
[exilis Richards, 1968:254, incorrect subsequent spelling]
exul (Tkalcu, 1974a:42 [Megabombus]) unjustified emendation
5 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region, Arctic border.

Bombus (Th.) tricornis Radoszkowski
tricornis Radoszkowski, 1888:319, examined
3 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Palaearctic Region, Oriental border.

Bombus (Th.) atripes Smith
atripes Smith, 1852a:44, examined
1 name

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: Oriental Region.

trinominatus-group of species

Bombus (Th.) digressus (Milliron)
digressus (Milliron, 1962:730 [Megabombus]) examined
1 name

COMMENT: Until 1990 this species was known from very few specimens. However, recent collections have shown it to have been overlooked.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: S Nearctic, N Neotropical Regions.

Bombus (Th.) weisi Friese
laboriosus Smith, 1861:153, examined, not of Fabricius, 1804:352 (= Emphoropsis laboriosus (Fabricius))
weisi Friese, 1903:253, examined
nigrodorsalis Franklin, 1907:90, examined
6 names

NOMENCLATURE: The lectotype female of B. weisi by designation of Milliron (1960:98) was considered conspecific with B. nigrodorsalis by Labougle (1990). He then used B. weisi (the oldest available name) as the valid name for this species. However, a case could be made in favour of the use of either name.

For Labougle's (1990) use of this previously unused senior synonym to be considered by ICZN as a prima facie case of upsetting the use of a long-accepted name in its accustomed meaning (ICZN, 1999: Article 23), the name B. weisi should not have been used in this sense in the preceding fifty years; and at least 10 authors should have used the junior name, B. nigrodorsalis, in at least 25 publications over at least 10 years (ICZN, 1999: Article 23.9.1.2). As far as I am aware, no other admissable publications have used B. weisi (Williams, 1995, disclaimed any nomenclatural action in a list of names for material examined), although publications using the junior name B. nigrodorsalis Franklin for this species since 1950 are more common, including Milliron (1961, 1962, 1971, 1973a), Laverty et al. (1984), Labougle et al. (1985), Williams (1985b) and Asperen de Boer (1992b). Other such references may exist, therefore this may be seen as a borderline case.

On the other hand, a change of valid name from B. nigrodorsalis to B. weisi does not appear to be a serious disruption of common usage according to ICZN's criteria, so there is no obvious need for action to retain B. nigrodorsalis and I have continued to use B. weisi.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: S Nearctic, N Neotropical Regions.

Bombus (Th.) trinominatus Dalla Torre
modestus Smith, 1861:153, examined, not of Eversmann, 1852:134 (= B. modestus Eversmann)
trinominatus Dalla Torre, 1890:139, replacement name for modestus Smith, 1861:153
xelajuensis Asperen de Boer, 1992b:162
3 names

TAXONOMIC STATUS: The description of B. xelajuensis shows that this nominal taxon, known from a single location, diverges only slightly in colour pattern and morphology from the otherwise restricted and uncommon mountain species B. trinominatus. Therefore it seems most likely to be conspecific with B. trinominatus, with a slightly different colour pattern. From COI barcodes, these taxa appear likely to be separate species. More evidence is awaited.

DISTRIBUTION: S Nearctic Region.

pensylvanicus-group of species

Bombus (Th.) fervidus (Fabricius)
feruida [fervida] (Fabricius, 1798:274 [Apis])
?Californicus Smith, 1854:400, examined
Dumoucheli Radoszkowski, 1884:78
sonomæ [sonomae] Howard, 1902:pl. II, examined
13 names

TAXONOMIC STATUS: B. fervidus and B. californicus have been regarded both as conspecific (e.g. Milliron, 1973a; Labougle, 1990) and as separate species (e.g. Franklin, 1913; Stephen, 1957; Thorp et al., 1983; Poole, 1996). However, both Franklin (1913:239) and Stephen (1957) also considered the possibility that they are conspecific as quite reasonable (click here for colour variation diagrams for workers).

Many specimens from the north west of North America show a reduction in the extent of the yellow bands on the scutellum and gastral terga I-III and appear to be intermediate or recombinant individuals. Indeed, Stephen's (1957:32) figure 2 shows several patterns that could represent a continuum in variation between the two forms (see also the comments on B. terricola).

Evidence from comparisons of DNA sequences from the 16S gene is consistent with the two taxa being conspecific (Cameron et al., 2007 [pdf]), a view supported by evidence from COI barcodes.

NOMENCLATURE: Apis feruida is the original spelling in Fabricius (1798). The orthography of this publication employs 'u' in place of 'v' widely, a common practice of the period. This convention has since changed and subsequent authors have consistently used 'v' for B. fervidus.

In fact, whatever the interpretation of the Code, pragmatically it matters little which spelling of fervidus is used unless either of the spellings were to be published as the name of another taxon in Bombus. See the comments on the spelling of B. pensylvanicus.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: W Nearctic, E Nearctic, S Nearctic Regions.

Bombus (Th.) diligens Smith
diligens Smith, 1861:154, examined
dolichocephalus Handlirsch, 1888:244
2 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: S Nearctic Region.

Bombus (Th.) bellicosus Smith
thoracicus Sichel, 1862:121, not of Spinola, 1806:30 (= B. pascuorum (Scopoli))
bellicosus Smith, 1879:131, examined
Emiliae Dalla Torre, 1890:139, replacement name for thoracicus Sichel, 1862:121
7 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: E Neotropical Region, S Neotropical border.

Bombus (Th.) opifex Smith
opifex Smith, 1879:133, examined
2 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: W Neotropical, E Neotropical Regions.

Bombus (Th.) rubriventris Lepeletier
rubriventris Lepeletier, [1835]:472, examined
1 name

TAXONOMIC STATUS: B. rubriventris is known from a single female specimen from 'St. Domingue'. This specimen has dark brown wings and the pubescence is extensively black, except that most of the hairs of the thorax are grey-tipped, and the hairs of gastral terga II-IV are bright red.

This colour pattern resembles the Andean B. excellens, although the pubescence of B. rubriventris is much shorter and more even; the oculo-malar area is nearly square (rather than nearly twice as long as the basal breadth of mandible); and tergum VI is raised subapically. Franklin (1913) had not seen B. rubriventris but suggested that it was probably a 'freak specimen' of B. carolinus (a misidentification, = B. excellens). Milliron (1973a) had examined B. rubriventris and considered the morphological characters to be very much like those of B. bellicosus. However, B. rubriventris can be distinguished by the much finer punctures in the centre of the clypeus and by an absence of a median ridge on tergum VI. I consider B. rubriventris to be more similar in these characters to B. opifex, although it can be distinguished from that species by a pair of characteristically slightly recessed bands of fine punctures extending anteriorly from the ocello-ocular areas and by a shallow median groove in the subapically raised area of tergum VI.

The colour pattern is very distinctive among non-Andean bumblebees in South America and does not appear to be the result of abnormal colour development. The specimen has had the gaster glued back into place, although the characters of both the head and gaster appear to be distinctive, so there is no reason to believe that the specimen is a composite and not genuine (Williams, 2014).

PHOTOGRAPH: Only a single specimen is known, in the Hope Museum collection, Oxford.

IUCN CONSERVATION STATUS: Preliminary assessment as presumed EXTINCT (Williams & Osborne, 2009; Williams, 2014) because it is unrecorded (IUCN, 2001, 2008) since Lepeletier (1835) from the specimen of unknown date.

Bombus (Th.) medius Cresson
medius Cresson, 1863:97
1 name

TAXONOMIC STATUS: See comments on B.steindachneri.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: S Nearctic, N Neotropical Regions.

Bombus (Th.) steindachneri Handlirsch
Steindachneri Handlirsch, 1888:239
1 name

TAXONOMIC STATUS: B. medius and B. steindachneri have been regarded both as separate species (Milliron, 1973a; Labougle, 1990) and as conspecific (G. Chavarría, pers. com.).

Labougle (1990) reports that 'Although the chromatic differences between B. medius and B. steindachneri are conspicuous, the male genitalia are extremely similar'. Labougle listed four character differences from the male genitalia and I can confirm two of these: (1) that the head of the penis valve of B. steindachneri has fewer fine teeth or serrations; and (2) that the interior process of the volsella (misinterpreted as the preapical tooth of the 'gonostylus'; for discussion of homologies see Williams, 1991 [pdf] ) of B. steindacheri is narrower. However, I have examined only a few males and these characters might be expected to vary among other individuals. Labougle (1990) continued: 'The lack of chromatic and morphological intermediates supports the idea of two different species'.

Until more evidence to the contrary is available from critical studies of patterns of variation, I shall treat them as two separate species.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: S Nearctic Region.

Bombus (Th.) mexicanus Cresson
mexicanus Cresson, 1878:187
3 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: S Nearctic, N Neotropical Regions, W Neotropical border.

Bombus (Th.) brevivillus Franklin
brevivillus Franklin, 1913:119, examined
?abditus (Tkalcu, 1966:271 [Megabombus])
applanatus Francoso, Oliveira & Arias, 2015:9
4 names

TAXONOMIC STATUS: The single known female of B. abditus was described as originating from 'Rep. de Guinée Beyla' (equatorial Africa). However, it is indistinguishable from B. brevivillus according to Sakagami (1976:427) and probably represents an introduced or mislabelled individual (Michener, 1979).

The recently described B. applanatus appears to be morphologically identical to B. brevivillus.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: E Neotropical Region.

Bombus (Th.) pensylvanicus (DeGeer)
penfylvanica [pensylvanica] (DeGeer, 1773:575 [Apis])
americanorum Fabricius, 1804:346
sonòrus [sonorus] Say, 1837:413
pallidus Cresson, 1863:92
Pensylvanicus Cresson, 1863:94
flavodorsalis Franklin, 1913:409
pennsylvanicus Hurd, 1979:2204, unjustified emendation
13 names

TAXONOMIC STATUS: B. pensylvanicus and B. sonorus have been regarded both as conspecific (e.g. Milliron, 1973a; Labougle et al., 1985; Labougle, 1990; Poole, 1996) and as separate species (e.g. Franklin, 1913 [but see p. 239]; Stephen, 1957; Thorp et al., 1983; S. Cameron in litt.) (click here for colour variation diagrams for workers).

From the few males from the United States (not Mexico) that I have examined in detail, there appear to be subtle differences in the male genitalia (e.g. in the shape of the penis valve head). However, Labougle (1990) reports that the two 'forms are geographically intermixed in México, and chromatically intermediate specimens occur, mainly in northeastern México and southwestern Texas'. He went on to say that 'In fact, it is sometimes difficult to place a Mexican specimen in either subspecies because there are specimens with the coloration of the scutellum and the punctation of the clypeus intermediate between the two taxa. Average differences of certain proportions are found ... but do not differentiate all specimens'. G. Chavarría (pers. com.) also believes that intermediate specimens occur in Mexico and that they are conspecific. Taking an extreme viewpoint, it is even possible to see the 'typical' B. sonorus colour pattern as intermediate between B. pensylvanicus (in the strict sense) and the extreme pale form that has the thoracic dorsum and gastral tergum I entirely yellow (flavodorsalis, see Thorp et al., 1983: fig. 137b). Evidence from comparisons of DNA sequences from five genes is consistent with the two taxa being conspecific (Cameron et al., 2007 [pdf]), which is supported by evidence from COI barcodes.

NOMENCLATURE: Apis penfylvanica is the original spelling in DeGeer (1773). The orthography of this publication employs a long 's' (similar to 'f' or 'f'), a common practice of the period. This convention has since changed and subsequent authors (e.g. Cresson, 1863) have consistently used 's' for B. pensylvanicus.

Technically, according to the Code (ICZN, 1999: Article 32), pensylvanicus with just two 'n's is the correct original spelling, to be preserved unaltered unless it is demonstrably incorrect under Article 32.5. Article 32.5.1 states that clear evidence of an inadvertent error is only admissable if it lies within the original publication, without recourse to any external source of information (DeGeer, 1773, spelled Penfylvanie and penfylvanica consistently in this way). Any intentional change to that spelling in a subsequent publication is an unjustified emendation under Article 33.2.

In fact, whatever the interpretation of the Code, pragmatically it matters little which spelling of pensylvanicus is used unless either of the spellings were to be published as the name for another taxon in Bombus. No doubt many will prefer to use B. pennsylvanicus, although the name does appear as B. pensylvanicus in the recent checklist by Poole (1996) (and by analogy, the similar spelling of Vespula pensylvanica (Saussure) has been accepted, e.g. by Akre et al., 1980; Edwards, 1980).

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: W Nearctic, E Nearctic, S Nearctic Regions.

INTRODUCTIONS: This species was deliberately introduced into the Philippines, but is not known to have persisted (Frison, 1925b).

Bombus (Th.) pullatus Franklin
niger Franklin, 1913:120, examined
pullatus Franklin, 1913:122, examined
1 name

TAXONOMIC STATUS: At least four species of the subgenus Thoracobombus from Central and South America have many individuals for which the pubescence is almost entirely black. The genitalia of the males are quite distinctive, but association of the conspecific females with these males has caused problems.

In the original description of B. niger, Franklin stated that 'atratus is possibly the male of niger' (p. 121), whereas in the original description of B. atratus he stated both that 'Niger may represent the females of this species' (p. 118) and that 'This may be the true male of kohli' (p. 119). B. niger was described from a syntype series of four queens and four workers, of which one queen in the Smithsonian collection carries, amongst others, a red label 'LECTOTYPE / Bombus / niger Franklin / H.E.Milliron '59' and a label 'Boquete / Chiriqui'. In my opinion, this lectotype of B. niger is conspecific with B. pullatus (as suggested by Labougle, 1990, see also Milliron, 1962).

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: N Neotropical, W Neotropical Regions.

Bombus (Th.) brasiliensis Lepeletier
brasiliensis Lepeletier, [1835]:470, examined
3 names

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: E Neotropical Region.

Bombus (Th.) bahiensis Santos-Junior et al.
bahiensis Santos-Junior, Santos & Silveira, 2015:12
1 name

TAXONOMIC STATUS: This status of this species was confirmed recently from DNA data (Santos-Junior et al., 2015).

DISTRIBUTION: E Neotropical Region.

Bombus (Th.) pauloensis Friese
?azurea (Christ, 1791:129 [Apis])
atratus Franklin, 1913:118, examined, not of Friese, 1911:572 (= B. mucidus Gerstaecker)
nigriventris Friese, 1913:87
pauloënsis [pauloensis] Friese, 1913:87
16 names

TAXONOMIC STATUS: At least four species of the subgenus Thoracobombus from Central and South America have many individuals for which the pubescence is almost entirely black. The genitalia of the males are quite distinctive, but association of the conspecific females with these males has caused problems.

A possibility is that this variable species is the Apis azurea of Christ (1791). I know of no type specimens and the type locality was said to be in Africa ('Ist in Afrika am Vorgebürg der guten Hofnung zu Haus'). The description and figure of the colour pattern do not agree with any African bees that I have been able to trace, but do resemble closely the yellow-banded individuals of the South American B. niger, the Central American B. medius Cresson, and the South American B. transversalis (Olivier) (although for the last named species the yellow bands on the thorax are usually broader). Among the specimens to hand, the wings do appear slightly more 'Schwarzblaue' for B. niger, as described for A. azurea, although these grounds seem slim justification from which to establish the application of a name.

NOMENCLATURE: B. azureus is possibly the oldest available name for this species.

Milliron (1962), without mention of the name B. azureus, first regarded B. atratus and B. niger as conspecific and, following the Principle of First Reviser (ICZN, 1999: Article 24), chose B. atratus as the valid name for the species.

Unfortunately, B. atratus Franklin, 1913, is a junior primary homonym of B. mucidus var. atratus Friese, 1911 (deemed to be subspecific, see ICZN, 1999: Article 45.6), therefore B. atratus Franklin is invalid (ICZN, 1999: Article 57.2).

The name B. azureus has not been used since the original publication. The name B. atratus has been used for this species since 1950 (e.g. Moure & Sakagami, 1962; Sakagami & Zucchi, 1965; Sakagami et al., 1967; Milliron, 1971, 1973a; Sakagami, 1976; Ito, 1985; Labougle, 1990; Varela, 1992; Silveira & Cure, 1993). It was suggested that, in the interests of stability (ICZN, 1999: Article 23), prevailing usage be maintained. This will require an application be made to ICZN to use its Plenary Power to suppress the senior homonym (ICZN, 1999: Article 78). This would achieve both an unambiguous, valid name for this species (see the comments on B. muscorum) and also help to protect the validity of the names B. medius and B. transversalis from future change (in prep.). However, South American bumblebee specialists have adopted the name B. pauloensis.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: W Neotropical, E Neotropical, S Neotropical Regions.

Bombus (Th.) transversalis (Olivier)
tranfverfalis [transversalis] (Olivier, 1789:65 [Apis])
Cajennenfis [cajennensis] (Fabricius, 1798:273 [Apis])
incarum Franklin, 1913:131, examined
6 names

NOMENCLATURE: The orthography of Olivier (1789) and Fabricius (1798) employs a long 's' (similar to 'f' or 'f'), a common practice of the period. This convention has since changed and recent authors have consistently used 's'.

MORPHOLOGY: photos of male genitalia.

DISTRIBUTION: W Neotropical, E Neotropical Regions.